Manufacture of artificial protein filaments



Feb. 1, 1949.

R. H. K. THOMSON MANUFACTURE OF ARTIFICIAL PROTEIN FILAMENTS Filed Aug. 21, 1944 iWoshing Both coagulating But h Spinneret Insolubilizing Both FIG.

Drawing Chamber [8 Honking Device Winding Roll /7 Steam H oi Air Drier Hot Air Drier Woshing T unk Formaldehyde B ath FIG. 3.

Rewinding H01 Air Drier Boiling Water Tank Inventor ROBIN H. K. THOMSON Attorneys Patented Feb. 1, 1?49 ,MANUFACTURE OF ARTIFICIAL PROTEIN FILAMEN TS Robin H. K. Thomson, Kilwinning, Scotland, as-

signor to Imperial Chemical Industries Limited, a corporation of Great Britain Application August 21, 1944, Serial No. 550,487 In Great Britain October 20, 1943 12 Claims.

The present invention relates to the manufacture of filaments of coagulated and insolubilised protein material for textile purposes, and more particularly to a process for the improvement of, filaments obtained by a wet spinning process from solutions of casein or vegetable globulins, which have been subjected in coagulated filamentary form to the action of an acidified aqueous solution of formaldehyde or other aqueous insolubilising bath adapted to render the coagulated protein filament capable of withstanding hot Weakly acid or alkaline solutions such as are used in dyeing and laundering.

In the production of insolubilised wet spun protein filaments it is usual to apply a stretch to the filament at some part of the process, and to efiect at least a partial stabilisation of the length of the stretched filament by means of the baths through which it passes; so that when the tension is released. it will not shrink excessively in a longitudinal direction. This stretching and length stabilisation may be effected prior to the commencement of the insolubilisation, or in the course of the insolubilisation of the coagulated protein. In either case the insolubilised filaments obtained after the release of any tension upon them are substantially unstrained and exhibit little or no bi-reiringency.

. It is known that textile filaments of various kinds can be improved in strength by steaming them in stretched condition and drying them the said insolubilised filaments, retaining the off while still stretched, but the'improvement so obtained is usually lost when the filaments are subsequently subjected in the untensioned condition to the action of boiling water or steam..

We have now found that when insolubilised, crimped or uncrimped, protein filaments are wet stretched and are subsequently subjected to the action of formaldehyde for a period of time, and set by drying them at high temperature, both of these operations being conducted while they are held stretched, they become markedly birefringent and their untensioned length and strength are increased, and the longitudinal shrinkage and loss of strength when the resulting filaments are subsequently treated for example with boiling water in the untensioned condition is less than when the formaldehyde treatment is omitted, but is sufficient to give thema crimp.

According to the present invention, therefore, the process for the production of improved and crimped filaments from insolubilised filaments obtained by wet-spinning from solutions of casein or vegetable globulins comprises wet-stretching filaments in the stretched condition while subjecting them to raised temperature and treatment with formaldehyde, and thereafter Withdrawing the tension and effecting the shrinkage of the thus treated filaments to the desired degree of crimp.

If desired the wet stretched filaments may be dried off under tension at raised temperature before the formaldehyde treatment is commenced. The drying is conducted at'a temperature not less than C., and if desired the filaments may be further heated to a temperature of to C. before commencing the formaldehyde treatment. l

The Wet stretching is advantageously carried out with hot water or steam, and the extent to which the insolubilised filaments can be stretched without breaking, may depend on the nature of the treatment they have received in their production, but it will usually be possible to apply a stretch of from 50 to 100 per cent. The stretched and if desired dried filaments may then be immersed in commercial formalin solution, i. e. a solution of formaldehyde of a lower acidity than that used in the previous insolubilisation step and left in contact with the solution for several hours if it is used at ordinary temperature. However, instead of immersing the filaments in a formaldehyde solution they can be subjected to an atmosphere of formaldehyde vapour. The formaldehyde treated filaments may then be washed until their odour is faint and are then dried at a raised temperature not below about 80 C. Preferably the temperature is allowed is to rise somewhat about 100 C.when they havebeen dried. The tension on the filaments may then be released. At this stage they are straight, and silk-like, but on immersion in hot water they shrink, and after drying in untensioned condition have a desirable woolly crimp.

In putting the invention into efiect it is convenient to carry out the wet stretching of the insolubilised filament, and the subsequent steps in which it is maintained in stretched condition, with a continuous length offilament, which implies thatthe whole of the preceding steps in the production of filaments, including the insolubilisation treatment, is also carried out before cutting the filaments.

It is desirable to wash the insolubilised filaments at least substantially free from the insolubilising solution before the wet stretching step is carried out. Before the wet stretching step is carried out it is permissible to relieve the insolubilised filaments of any tension under which they break in the continuity, for the washed insolu bilised filaments, whether or not already under tension, may be directly subjected to the Wet stretching step.

A more complete understanding of the procedures of this invention may be had by refer-- ence to the accompanying drawing which diagrammatically illustrates the procedural steps involved. In the drawing, 7

Figure 1 shows the three preliminary stages of spinning, insolubilizing and washing of the filaments;

Figure 2 shows the subsequent steps of' drying and hot drawing of the filaments;

Figure 3 illustrates the steps of treating the filaments while under tension to insolubilizing, washing and hot drying steps, and

Figure 4 shows the steps of rewinding the tensioned filaments into hank formand subsequently treating the untensioned filaments to boiling and drying.

Referring in detail to the drawings, the filament 2 is 'formed by extruding a protein solutionthrough the spinneret l into the 'coagulated :bath 6 and thence to the 'hanking device Where hanks 8 are formed. The hanks are then placed in the insolubilizing bath Ill, where the filaments are insolubilized, after'which they are passed into a washing bath i2. Since the drawing is only diagrammatic in nature, only'one washing tank is illustrated but it will be understood that several such tanks may be employed and that pure water or weak alkaline or other washing solutions may be employed.

From the washing tank, the filaments are passed to a hot air drier M where the filaments are and subjected to the drying action of hot air. Thence, the dried filaments are passed from winding the roll it to tension rollers I8 and '20 through the steam chamber 24 and are wound upon the winding roller 2-6 at a speed in excess of the speed of the tension rollers 18 and 25, so that the filaments are elongated while within the steam chamber 2 3 and subjected to the action of the steam passed through this chamber.

The filaments are retained under the tension produced during the winding operation upon the rollers or bobbins 23. In this condition, they are first immersed in an insolubilizing bath from where they are taken and immersedin the washing bath 32, Finally, while still under tension, the filaments are dried in the drying chamber 34 b hot air.

The bobbin of tensioned filament 28 is then rewcund onto a roller 36 so that .the filaments may be formed in hanks for further treatment in an untensioned condition. In the untensioned state, the filaments are immersedin .the boiling water tank .38. Finally, the filament Ihanks are dried in thehot air drying chamber 40.

The invention is illustrated ;by the .following example 7 Example The filaments employed as the -starting :ma-

terial' are prepared by coagulating in .a hot :acidi' fied :sodium --sulphate bath :under tension :a viscous aged solution of peanut protein in :dilute' aqueous sodium hydroxide solution, the protein solution being extruded into the coagulating bath through a multiple hole spinneret, and subsequently insolubilising the coagulated filaments in the untensioned condition in a bath consisti-ngcf a :nearlysaturated solution of sodium chloride containing 1 per cent formaldehyde and 1.75 per cent sulphuric acid for a period of 18 hours at 20 C., and then washin the filaments, treating them first, with an aqueous dispersion of Lissapol C, then with a dilute sodium car-' bonate solution, and then drying them 01? in hank "form. The use of the hot coagulating bath effects a sufficient stabilisation of their length to enable the insolubilisation treatment with the acidified saline formaldehyde solution to be car- :ried out in the untensioned condition. The treatment with the Lissapol dispersion confers a somewhat softer handle on the filaments, and the treatment with dilute sodium carbonate solution is intended to raise the pH of the filaments to a value of about 7, which is frequently -de-- sirable for dyeing purposes. The drying of :the filaments is carried out in hot air at 100 C. The resulting filaments have a considerable crimp, and exhibit little birefringence. Their tensile strength is approximately 8 kilograms per square millimetre, 'as calculated on their average thickness from the breaking stress in .an atmosphere of 5G-per cent. relative humidityat 20 C.

The dried filaments are then thoroughly damped in steam andzthe filaments aredrawn ofi from it through the stearn'itol a roller :01! they are wound helically under such tension that their taut length'is increasedabout '7 5 per cent.

The rollers carrying "the filaments in the stretched state are then immersed -.for 16 hours in commercial 'formalin'solution; The filaments v are then washed until substantially free from odourand dried in ai-rat 1110 C. under tension, and are then released from the tension. The resulting filaments have ho crimp and have an artificial silk-like appearance. They are relatively strongly bi refringent. Their tensile strength is approximately 12 kilograms per square .millimetre,ias calculated in the manner already referred to. "The resulting :filaments are now rewound sinto'zhank form and are immersed in boilin water in the 'untensioned condition for '10 minutes. They are then dried off in atliiil Cmwithout tension; as .a result of this treatment they acquire a useful degree of crimp and a wool-like appearance. They are then rehumidified. Their tensile strength .is approximately 9.7 kilograms per square millimetre, as -:calculated in the manner already referred to. They are intermediate in 'bi-refringency between the insolubilised filaments employed as thestarting material and the artificial sills-like filaments already'referred'to. I V "I claim:

'l. The process for obtaining an" improved, crimped, protein filament, which comprises wetstretching an inso'lubilized filament previously formed by wet-spinning-a protein solution of the group consisting "of vegetable globulin solutions andcasein-solutions, contacting thejtaut filament with formaldehyde, dryingthe'taut filament at a temperature or at least C., releasing the tension on the filament and thereafter contacting the filament in relaxed condition with boiling water. V

:2. The process for V obtaining an improved, crimped, :protein filament,- =which comprises stretching in steam ran insolubilized filament previously formed by Wet-spinning a vegetable globulin solution, contacting the taut filament with formaldehyde, drying the taut filament at a temperature of at least 80 C., releasing the tension on the filament and thereafter immersing the filament in relaxed condition in boiling water. 3. The process for obtaining an improved, crimped, protein filament which comprises stretching in steam a formaldehyde-insolubilized filament previously formed by wet-spinnin a vegetable globulin solution, drying the taut filament at a temperature within the range of from 80 C. to 120 C., immersing the taut filament in an aqueous formaldehyde solution, washing the -taut filament, drying the taut filament at a temperature of at least 80 C., releasing the tension on the filament and thereafter immersing the filament in relaxed condition in boiling water.

4. The process for obtaining an improved, crimped, protein filament, which comprises stretching in steam a washed, formaldehyde-insolubilized filament previously formed by wetspinning a sodium hydroxide peanut protein solution, drying the taut filament at a temperature within the range of from 100 C. to 120 C., immersing the taut filament in a formalin solu tion, washing the taut filament, drying the taut filament at a temperature of at least 100 0., releasing the tension on the filament and thereafter immersing the filament in relaxed condition in boiling water.

5. A crimped protein filament formed according to the process set forth in claim 1.

6. A crimped protein filament formed according to the process set forth in claim 3.

7. A process for producing crimped, protein filaments of relatively high tensile strength which comprises Wet-spinning a protein solution into a coagulating medium, insolubilizing the resulting filaments in an acidic saline formaldehyde solution, stretching while wet the insolubilized filaments, contacting the taut filaments with formaldehyde, drying the resultingtaut filament at a temperature between 80 C. and 120 (3;, releasing the tension on the filaments and, thereafter, immersing the filament in a relaxed condition in boiling Water.

8. A crimped protein filament formed according to the process set forth in claim 7. r

9. A process for producing crimped, peanut protein filaments of relatively high tensile strength which comprises wet-spinning a solution of peanut protein dissolved in an aqueous sodium hydroxide solution into a coagulating medium, insolubilizing the resulting filaments in an acidic is j saline formaldehyde solution, stretching while strength which comprises wet-spinning a solution of peanut protein dissolved in an aqueous sodium hydroxide solution into a coagulating medium,

treating the resulting filaments in an acidic saline formaldehyde solution for a suificient length of 7 time to make the filaments completely resistant to the action of boiling water and hot dilute acid, stretching the insolubilized filaments in steam, immersing the taut filaments in an aqueous formaldehyde solution, drying the resulting taut filament at a temperature between 80 and 120 C.,

releasing the tension on the filaments and, thereafter, immersing the filament in a relaxed condition in boiling water.

11. The process of claim 10 wherein said treatment with acid saline formaldehyde is carried out ROBIN H. K. THOMSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

